Various devices have been utilized for containing fuel and other hazardous products to prevent the contamination of the surrounding environment. One such system is disclosed in U.S. Pat. No. 4,971,477. Another such device is disclosed in U.S. Pat. No. 5,390,713. This latter system, while attempting to reduce installation time, has several significant disadvantages. First, where multiple dispensers are serviced by a single multi-compartment underground storage tank, adjacent compartments are connected via internal piping, i.e., piping disposed on the interior of the storage tank and extending between the adjacent compartments. Due to variances in the fuel level of the adjacent compartments, the internal piping is subject to stress and hence breakage. This will lead to contamination of the higher grade gasoline. Also, this system utilizes only a single containment chamber for each above ground dispenser unit. Therefore, in pressure systems the pump is housed in the containment chamber under the dispenser unit. This makes access more difficult and further provides less area for servicing the pump.